George Zimmerman is escorted out of a van into the Seminole County Jail in Sanford, Florida on Sunday, June 3, 2012.

CNN

(CNN) -- In an initial interview with police just after the shooting death of 17-year-old Trayvon Martin, George Zimmerman described a life-and-death struggle that began when the youth "jumped out from the bushes."

The audio of the February 26 interview, made public late Wednesday, is part of discovery items released by Zimmerman's defense team. Zimmerman said Martin punched him repeatedly in the face.

"I started screaming for help. I couldn't see. I couldn't breathe," he said.

"He grabbed my head and started hitting it into the sidewalk," he said. "When he started doing that, I slid into the grass to try to get out from under him. ... I'm still yelling for help."

Martin, he said, put his hand over Zimmerman's mouth and nose and told him, "You're going to die tonight."

"When I slid, my jacket and my shirt came up, and when he said, 'You're going to die tonight,' I felt his hand go down my side, and I thought he was going for my firearm, so I grabbed it immediately, and as he banged my head again, I just pulled out my firearm and shot him."

When he did, he said Martin, who had been on top of him, fell away and said, "All right. You got it. You got it."

Zimmerman, 28, is charged with second-degree murder in Martin's February 26 shooting death. Zimmerman has said he shot Martin in self-defense, but Martin's family and civil rights activists from across the country said that Zimmerman, who is white and Hispanic, racially profiled Martin and ignored a 911 dispatcher's advice not to follow him.

Zimmerman said in the interview he was driving to the grocery store February 26 when he saw Martin walking in his neighborhood. He said he pulled over and called a police nonemergency number "to report a suspicious person."

He noted there had been some burglaries in the area, prompting him to start a neighborhood watch program. He said he had never seen Martin before and thought it odd that although it was raining, "he was just walking casually, not like he was trying to get out of the rain."

As he spoke to the dispatcher, he said Martin circled his vehicle but he "lost visual of him." At the same time, he said the dispatcher asked him his location. He said he wasn't sure of the name of the street he was on and got out of the vehicle to look for a street sign or an address on a home.

The dispatcher asked him if he was following Martin, he said, and he replied that he was "trying to find out where he went." The dispatcher told him, "We don't need you to do that," noting an officer was en route, he said.

Zimmeman said he was heading back to the vehicle when Martin jumped out, asking him, "What the f---'s your problem?"

He said he told Martin, "I don't have a problem," but the youth replied, "Now you have a problem," and attacked him. He said he fell backward after being punched in the nose, and "he was wailing on my head."

Zimmerman told police he yelled for help repeatedly and heard one man say he was going to call 911.